1. Field of the Invention
This invention relates generally to truck and/or trailer mounted portable devices for dispensing pavement repair materials, and specifically to such a portable device for dispensing tack oils used for repairing asphalt pavements.
2. Description of the Prior Art:
In the past, as many as three vehicles were sometimes needed to repair openings and potholes in asphalt pavements. One vehicle provided an air compressor for use with various pneumatic repair tools which were used to dress the hole or cavity to be filled. Another vehicle contained liquid asphalt tack material which would be sprayed into the dressed cavity, and a third vehicle would deliver asphalt mix material to the cavity. The asphalt would then be raked, compacted and leveled by hand to complete the repair.
U.S. Pat. No. 4,196,827, issued Apr. 8, 1980, entitled, "Portable Machine for Transporting Heated Asphalt Products for Use in Repairing Asphalt Pavement" shows a portable machine which was designed to incorporate all phases of the pavement repair into one mobile unit. The machine has a hopper for transporting asphalt mix, and has a reservoir below the hopper having a heat source. The reservoir contains liquid asphalt tack material. The heat source is used to heat the liquid tack material, and the tack material is used to heat the asphalt mix in the hopper by heat transfer. Asphalt tack material is also dispensed from the tack material tank by means of spray equipment connected to a discharge valve on the rear of the truck.
In spite of being less expensive to operate in terms of material and labor, the foregoing device possessed several disadvantages. Although the liquid asphalt tank is suitable for road oils and cutbacks, the liquid asphalt tank is not well suited for use with asphaltic cements. In addition, the liquid asphalt tank is not suited for use with asphalt emulsions, because the volatile contents of the emulsions would be driven off and dry out the material.
In order to overcome the above shortcomings, especially with respect to tack oils, mobile units have been provided with the tack oil tank located separately but on a common base with the hopper unit. The tack oil tank could then conveniently be supplied with its own heat source, specifically designed for the heat characteristics of emulsion oils and liquid asphalt oils.
In spite of these improvements, a problem sometimes occurs with separation of the tack oils contained in the separate tack oil tank. These oils are generally petroleum and animal fat products that are emulsified. Most such oils are intended for immediate use or otherwise the water content of the oil separates from the base material. Previously, the materials were remixed for use by using the spray applicator pump to recirculate the materials within the tank, or the materials were manually remixed. Both methods were inefficient and time consuming.
A need exists, therefore, for an improved method and apparatus for dispensing tack oil which prevents phase separation of the tack oil materials.